1. Field of the Invention
The present invention relates to digital cameras, and in particular relates to image sensor readout techniques with black level calibration.
2. Description of the Related Art
A digital camera is a camera that takes video or still photographs, or both, digitally by recording images by an image sensor. The image sensors most currently used are digital charge-coupled device (CCD) or complementary metal-oxide-semiconductor (CMOS) active pixel sensors.
To produce an image of high quality, a black level calibration is required in a readout process of an image sensor, wherein a temporal offset due to changing supply voltages, temperatures, and the like is compensated for.
A black level calibration design with high stability is called for.